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ar P. i!12 1,111113:11 1 - Soil samples were delivered,under chain of custody, to the California Department of Health Services(DHS)certified Pace Laboratories, Inc., for hazardous materials analyses. The samples were analyzed for petroleum hydrocarbons in accordance with recommendations of Table 2 of the"Tri-Regional Recommendations." A.3 WELL INSTALLATION The boreholes were completed as groundwater monitoring wells after drilling. The wells are . constructed of 4-inch-diameter Schedule 40 PVC flush-threaded casing. The screened interval consists of 0.010-inch slotted casing,placed from 20 feet below the water table to 5 feet above it. A threaded end plug was placed on the bottom of each well. ' A filter pack of clean No. 2/16 Lonestar sand was placed in the annular space around the well f screen to approximately 2 feet above the top of the screen. The sand was scaled with a Bentonite Plug 1 foot thick and hydrated with deionized water. A surface seal was then created by placing a neat cement grout to the surface with a tremie pipe. Each on-site well is about 50 feet:seep and have 25 foot screen. The wells were secured from unauthorized entry on the surface in a slightly raised, 12-inch- diameter traffic-rated,water-tight steel traffic box that requires a special wrench to open. The F - traffi c boxes were set in concrete. Each well was further secured from unauthorized entry with a Iocking well cap. Each weII was equipped with a well to containing as well depth,screen intervals,diameter,contact. g g pertinent information such Li A.4 WELL DEVELOPMENT r' The.wells (RWI, RW2, and RW3 ) were developed on 16 and 17 May 1990. Development : consisted of surging the screened interval of the well with a 4-inch flapper valve surge block for approximately 15 minutes. The wells then were purged,with a submersible electric pump,of 2-6 f ' casing volumes of water. The surging and pumpingrepeated until werethe water was free of silt and the appearance of turbidity. About 120 gallons of water was evacuated from each well r Records of the well development methods and volumes of water purged was maintained. All purge water was contained on the site in properly labeled 55-gallon drums. Purged water will be disposed of at an appropriate facility on the basis of the laboratory analytical results. ; z A.5 WELL,SURVEY The elevation of the top and the Christy box of each well casing were surveyed relative to an established datum (wells MW2 and MW3)using a Lietz C-3 automatic level and stadia rod. A �. small notch was cut in the top of the well casing to mark the survey point,to ensure that this ai point is used for all future water level measurements. A loop originating and ending at the datum t was closed to:-0.01 feet according to standard methods described by Brinker and Wolfe(1977). ti. c47/l3942/ua90/Ppa A_2 v